1. Field of the Invention
The invention concerns a piston pump for thick matter with at least a hydraulic operated pump cylinder, of which the pump piston is connected to the piston of a hydraulic drive cylinder by a common piston rod, and with a water box situated between the pump cylinder and the drive cylinder, through which the piston rod passes and which has a service opening at the top and accessible from above and a water outlet nozzle located at the bottom end.
2. Description of the Related Art
Piston pumps of this type are employed for transporting thick matter such as concrete, sewage sludge, excavated tunnel material and like. The water box is associated above all with a cleaning function: the common piston rod extending through the water box is freed or kept free of impurities from the area of the pump cylinder, in order to prevent contamination of the hydraulic fluids. In addition, the water box is associated with an important assembly and maintenance function: the pumping pistons which are exposed to a more or less greater abrasion, depending upon the abrasives of the media being conveyed, must be changed out at predetermined time intervals. They are thus releasably connected to the piston rod. The assembly occurs within the water box through the service opening at the top end. As inherently necessary for construction, the water box is located in the central area of a movable or stationary pump base, in which also other elements or aggregates of the pump assembly are located. The space available above the water box is thus most often very narrow, so that the access opening and the inside of the water box are only accessible from the outside with difficulty. The assembly of the pumping piston is further complicated thereby, that the pumping piston which is to be positioned in a defined mounting position has a high weight and the fasteners, such as screws and nuts, are to be assembled at positions not visible from the outside. It occasionally happens that during the assembly process a screw or a nut falls to the bottom of the water box and must be search for blindly and with great difficulty.